The invention involves a method and apparatus for providing security for computer software. There have been a number of systems adopted for securing software including codes within the program itself, as well as interaction with certain external elements used through various ports for inputting certain information in the computer.
For the software sold in large quantities and in disk form, it is relatively easy for the purchasers of the software to make unlimited copies and distribute them as they desire. As a result of this copying, substantial revenues have been lost because of the availability of the software and the difficulty of prohibiting copying beyond that necessary for each individual user. Approaches in attempting to prevent this type of copying are security systems integrated with the software, certain licensing techniques, which allegedly prohibit the user from making copies other than back-up or archival copies for their own personal use, and interactive systems with certain external attachments.
Particularly for software where the security system resides solely in the program, it has become relatively easy to break the code used in protecting a particular software scheme. In fact, there have been marketed other programs solely for the purposes of breaking these codes. They enable buyers to duplicate protective software and avoid any internal security measures. Once the code is voided or broken, the user can then recopy the program and distribute it through computer networks to literally thousands of other unauthorized users.
There have been a number of approaches in attempting to overcome this problem. An example of these is demonstrated in U.S. Pat. No. 4,446,519, issued to Thomas, on May 1, 1984, entitled Method And Apparatus For Providing Security For Computer Software (hereinafter the Thomas patent). This patent relates to an electronic security device which utilizes a plug-in circuit board element, along with each legitimately purchased software package. The software packages are programmed to establish a communication such that when a disk or tape is loaded into the working memory of the computer, the program sequence is commenced. The software generates coded interrogation signals which are transmitted to the electronic security device. The device includes logic circuit for evaluation of interrogation signals generated by software. If the security device is the correct one, the device will recognize the interrogation signals and transmit the proper coded response signals to the working memory of the computer. Only if the software in the working memory receives the proper response signals from the ESD, the software will then generate command signals to the computer which cause execution of the program. If the response signals are not received by the working memory containing the software program, the command signals are not generated and the program cannot be executed by the computer.
In another embodiment discussed in the Thomas patent, it is stated that a failure to receive proper response signals from ESD can even require the program in the working memory to be erased or scrambled in a fashion that does not even permit the program pirate to determine the nature of the incorrect response signal.
The problem with this approach is that it still enables copiers and pirates to break the code, because the code is ultimately dependent on the software. For example, if a system simply fails to execute the program, the system can be reprogrammed to generate enough interrogation signals until the proper code is ultimately reached. Once reached, the ESD will then emit the correct signal to complete execution of the program. Even in a situation where the proper response signal is not received by the working memory and the program can be scrambled, the computer program can be rebooted and various codes imparted to the security device until the proper code is ultimately generated in which, in case the correct signal will ultimately be transmitted for completion of execution of the program. Thus the systems discussed by Thomas are deficient, because of the prospect of breaking the code.
The invention described herein, overcomes the problems in devising security codes for software. The invention involves the use of a key which is loaded into a port of the computer. The key generates a binary, or other types of coded signals. The computer program includes an evaluation sequence such that the program will be executed only upon receipt of a predetermined coded signal. The key is not software dependent on receiving any signal from the computer, but generates its own signal which is preselected at the time the software and the key are sold. If the correct signal is not received by the program, it simply shuts down. There is no programming device which can devise various sequences for breaking the code and enabling the program to be executed. Rather, the only way the code can be broken is by arriving at a key which will work properly with the disk or tape which operates as a result of the coded signal transmitted by the key. With this system, it is literally impossible for the code to be broken and is immune to other code breaking programs.
The above has been a brief discussion of the problems of the prior art and the advantages of the invention. Other advantages will be perceived by those skilled in the art in the detailed description of the preferred embodiment which follows.